An Iran-based human rights group says dozens of Iranian security personnel have raided a prison ward housing minority Sunni inmates in the city of Karaj, beating the prisoners and taking their belongings.

In a report published Thursday, Iran’s Human Rights Activist News Agency (HRANA) said it learned of Tuesday’s incident at the Rajaei Shahr prison in Karaj’s Gohardasht district from an informed source.

HRANA, one of the few Iranian rights groups gathering reliable information from inside Iran, quoted the source as saying the prison raid targeted a ward housing Sunnis detained for their religious and political activities.

HRANA’s source said about 30 intelligence ministry agents and 50 Special Forces of the prison raided the ward at 11 p.m. Tuesday local time, smashing and removing personal belongings of the inmates and beating them as they brought those inmates to an open area of the prison, where they were kept until 2 a.m. Wednesday. HRANA’s source also accused the Iranian Shiite security forces of insulting the Sunni prisoners’ religious beliefs during the raid.

HRANA said its source reported that prison authorities denied medical care to Sunni inmates who were wounded during the raid. But the source said three prisoners from the ward, whose names were published in the HRANA report, were treated in the prison’s medical facility for existing health problems, while two other named prisoners were transferred to a hospital outside the prison. There were no reports of the Karaj prison incident or its aftermath in Iranian state media.

Exiled Iranian rights groups such as Iran Human Rights Monitor and the Center for Human Rights in Iran have reported previous cases of Iranian authorities using harsh tactics against Sunnis and other prisoners of conscience at Karaj’s Rajaei Shahr prison in recent years. They said prisoners have been deprived of basic rights such as clothes, medicine and meetings with family members.